/Engine/Source/Editor/LevelEditor/Public/LevelEditor.h
Spawns a new sequencer tab if one doesn't exist already
virtual [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [SDockTab](API\Runtime\Slate\Widgets\Docking\SDockTab) > AttachSequencer ( [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > SequencerWidget, [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< class [IAssetEditorInstance](API\Editor\UnrealEd\Subsystems\IAssetEditorInstance) > SequencerAssetEditor )